High-speed cineradiographic studies are being performed to evaluate left ventricular hypertrophy models, one produced by aortic stenosis and the other by the repeated injections of large doses of epinephrine. In addition to these studies we are continuing on with our quantitative analysis of the motion of the canine valves which again requires the use of biplanar high-speed cineradiography. Another study utilizing this instrument is the examination of the oscillatory dynamics of the right ventricular wall. Our laboratory is currently conducting a number of studies on the toxicity of currently available radiopaque materials. These studies involve hepatotoxicity of contrast media and the effects of these agents on the cerebral circulation. Leukocytes under certain controlled circumstances are capable of damaging the endothelial surface of the veins. We are currently examining whether these same effects occur in the arterial circulation. Another project involves the use of autologous skeletal muscle implant into the damaged myocardium. The muscle transplant has an intact circulation. We are also studying the effects of helium oxygen breathing mixtures on various cardiac conduction parameters.